that almost sounds like you are a tooth off on the distributor.

 

You misunderstand what CASE relearn is. It only recalibrates misfire detection. CASE relearn will not change your timing.

Like dchan says, maybe off a tooth on the distributor.

 

I thougt so too, but if I advance it 1 tooth, it backfires, and doesn' t start at all! Confirnmed multiple times.I' ve tried everything mechanical...Plus, I've read, that someone had counted, that moving one tooth, gives 50 degrees deviation... I forgot to mention, changing the coil as well. I don't know, whether changing the ICM, when it's fully functional makes sense... There are no trouble codes. There used to be P1345, but somehow disapeared, due to a strange event: I started the engine with a disconected cam sensor, and rapidly reved the engine. It backfired, and stalled. After that I conected the cam sensor, started it up, and the code has'n t popped any more. There wasn't any mechanical damage to the plastic, plenum cover, as someone, probably would ask. The MAP sensor is ok too, the engine idles s mooth, I'm not experiencing any performance issues... Just the timing reading on the diag. tool.

 

You misunderstand what CASE relearn is. It only recalibrates misfire detection. CASE relearn will not change your timing.

Got it! That's what I needed to know. So the digging goes on... The question is, should I go on digging, or should I stick to the saying: "If it ain't broke- don't fix it" :lol: I' m just worried, that something may go wrong in the future, if that reading has physical appearance... Would a timing lght- gun give a realistic view on the timing? Or should I cut openings, between the terminals of a distributor cap, and observe the angle of the spark- real time... :think:

 

Did you try retard timing by one tooth?

The computer is looking at all the info it's getting and trying to control the timing if you are already advanced one tooth, the computer tries to (usually sucessfully) retard the timing. If you get tio far advanced, the computer will not be able to retard the timing far enough to get the ingine to run.

 

Yes, I tried, but it was before changing the timing set, and dist-gear, and the engine ran awfull... I should probably give it one more go...

 

http://www.john-stichnoth.com/Distribut ... edure.html

Check this article.

DC

 

While I would not suggest running the engine without the distributor hold down, you might want to try this. It sounds like you have a way to monitor your timing.

Remove the hold down which includes the "key"that sets the distributor. Try slowly turning the distributor and see if you can get it to 0. With the engine RPM at about 1000-1200. If you can do this, you may find which direction your distributor is off if it is off a tooth.

 

The mistake many people make is that the rotor position needs to be off a certain amount as you insert the distributor it will rotate to its final position.

 

While I would not suggest running the engine without the distributor hold down, you might want to try this. It sounds like you have a way to monitor your timing.

Remove the hold down which includes the "key"that sets the distributor. Try slowly turning the distributor and see if you can get it to 0. With the engine RPM at about 1000-1200. If you can do this, you may find which direction your distributor is off if it is off a tooth.

By loosening the hold down and turning the distributor you will change the timing enough to notice a difference, whether this corrects it or not I do not know.

 

By loosening the hold down and turning the distributor you will change the timing enough to notice a difference, whether this corrects it or not I do not know.

Correct. Before we had computers to make these adjustments, this is the way we adjusted timing. My Accel distributor does not have the position key so i was able to get my timing right to "0" If you are at the limit of the computer's ability to correct, turning the distributor may allow you to get closer to that magic +-2. The computer will try to correct. Hopefully the correct direction. If you find you can get the timing "retard" to +-2 by turning the distributor about 15-20 degrees, then you will know you are off a tooth.

DC

 

Thanx guys, a lot for the input! Like I mentioned, I ve tried if not all, then most of the mechanical tests, including turning the distributor,with no hold-down bolt, while keeping the rpm at 1000-1200rpm, with no change to the -20-30 reading... What bothers me most, is the question: If the timing advance reading refers to the spark, would the engine even run, at -30 degrees...? It should be firing in the beginning of the exhaust stroke, thus not creating any power...or am I wrong..?

 

http://www.john-stichnoth.com/DistributorInstallProcedure.html

Check this article.

DC

I ve been through this article, and procedure allready... :lol:

 

The mistake many people make is that the rotor position needs to be off a certain amount as you insert the distributor it will rotate to its final position.

Yep, because of the spiral teeth- i know that.

 

Again- thank u guys, a lot, I m gonna get some sleep, since here the time is 2:30 AM, and tomorrow I m going on with the research. Please keep posting your thoughts, and I ll post updates, whenever i can. Night!

 

Maybe I should have been asking you what you are using to check the timing. There are 2 timing questions. What is the computer correcting the timing to, and what is the CMP retard.

A generic OBD II can only read what the computer corrected timing is at. What you need to check and adjust is the CMP Retard.

The computer can correct for a full tooth and will keep it right at 20 degrees until it runs out of room to retard or advance the timing any more. Usually at higher RPM's

Search "CMP Retard"

 

So, yesterday I came across a post, in the Blazer forum, about an android application-Car Gauge Pro- able to read the CMP retard, and downloaded it. Currently I'm using Torque Pro. Today I'm getting new OBD2 adapter as well, since the application requires BT, and my current adapter is wi-fi.Hopefully this app has the ability to tune the retard to spec. If this doesn't work, I've made an appointment in a shop, with professional diagnostic tools, so see what happens... :chevy:

 

Did you try retard timing by one tooth?

The computer is looking at all the info it's getting and trying to control the timing if you are already advanced one tooth, the computer tries to (usually sucessfully) retard the timing. If you get tio far advanced, the computer will not be able to retard the timing far enough to get the ingine to run.

I've tried it again- it won't start at all. I'm pretty certain, the problem lies at the CMP retard, and the ECM compensating it, as you suggested.

 

Download Dashcommand, it does have the ability to read the CMP pid, it's what I used to set mine.

 

CMP adjustment is for fine tuning only. It won't compensate for being off a tooth. There should be enough wiggle in the distributor hold down to get it set to 0. If you have to slot the distributor hold down then you are probably still off a tooth. This is for Gen 2 vans.

 

https://youtu.be/rPlYNtNkI9k

CMP adjustment is for fine tuning only. It won't compensate for being off a tooth. There should be enough wiggle in the distributor hold down to get it set to 0. If you have to slot the distributor hold down then you are probably still off a tooth. This is for Gen 2 vans.

Correct here. The computer will compensate for the tooth being off, but the CMP will tell you if you have the distributor in right.

When I got my van it was already off a tooth and I didn't know it. I went through the same process and found that besides being off a tooth, my gear had worn pretty badly so I got that new Accel distributor that came without the "keyed" hold down.

the CMP adjustment is to get the retard right in there but like mentioned , the computer will compensate for a lot of being off. The symptom when it was off was when ever I got up to a certain sustained RPM, I would get a cam sensor error. but the timing looked good all the time (except for some jitters until I replaced the whole distributor (bad gear))

The van should start even with the CMP being off unless you are 2 teeth off. It might throw codes and run rough but it should run.

 

Are you having driveability problems, or just concerned because the scan tool reports wacky timing? It could be that the scan tool is reading it wrong too. CMP retard is what you want to set to 0, it is like setting the base timing and the computer takes it from there. It will run a tooth off but should set a code P1345.

 

Download Dashcommand, it does have the ability to read the CMP pid, it's what I used to set mine.

10x Lowcab, I will have to download the Dashcommand, since the adapter I bought, for some reason(probably being lowest end chinese s---t) reads the GM Pids in Car Gauge Pro as unavailable for my van... :banghead:

 

Are you having driveability problems, or just concerned because the scan tool reports wacky timing? It could be that the scan tool is reading it wrong too. CMP retard is what you want to set to 0, it is like setting the base timing and the computer takes it from there. It will run a tooth off but should set a code P1345.

I don't have any driveability problems, but then again, I've never dealed with another such van,or truck,to be able, to make an exact comparison...It idles smooth, and has power all trough the rpm scale...I even drove it with 120mph shortly, when I bought it. I'm mainly concerned because of the reading of -20-38 ign timing, and the eventual consequences due to it. It''s been confirmed by few scanners.It used to have the P1345, but later on it disappeared, from itself I've tried to re- mesh the distributor, both- back, and forth, one tooth- it wouldn't start what so ever. Anyway I have an appointment in a shop tomorrow. The guys said their Bosh scan tool is internationally certified, still am not sure about the US vehicles, but we'll see...

 

I didn't even know an Astro Van could go 120mph let alone would I want to be in one at that speed!